Train-of-four fade — FRCA Primary MCQ

Correct answer: D — Residual non-depolarising neuromuscular block

Train-of-four fade indicates residual non-depolarising neuromuscular blockade at the neuromuscular junction. Mapleson D is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Uneven alveolar emptying is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Infrared gas analyser is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Airway laser fire risk is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. In Primary FRCA physics and measurement, the safest answer is the one that follows the underlying physical principle and the limitations of the device.

Reference: Davis and Kenny Basic Physics and Measurement in Anaesthesia; RCoA Primary FRCA syllabus